Development and evaluation of an instrument to assess social difficulties in routine oncology practice

Purpose: To develop and preliminarily evaluate a Social Difficulties Inventory (SDI) for use in oncology practice. Methods: Item generation from patients (n=96), staff (n=49) and the literature. Questions constructed and pre-tested (n=42) resulting in a 22-item questionnaire. Psychometric evaluation (n=271) assessed frequency of endorsement, factor structure, summated scales and construct validity followed by randomisation to criterion validity or test-retest arms. Results: Items met preset frequency of endorsement criteria. Factor analysis revealed a four-factor structure, three clearly definable, (1) Physical ability, (2) Providing for the family and (3) Contact with others, explaining 45.8% variance. Summated scales developed from these demonstrated good reliability (Cronbachs alpha > 0.7) and were used to test and confirmed construct validity. Several comparators from the Life Events and Difficulties Schedule (LEDS) and CAncer Rehabilitation Evaluation System Short Form (CARES-SF) tested criterion validity and majority agreements were moderate to good. Test–retest reliability was good with most kappa values > 0.6. One item was eliminated resulting in a 21-item questionnaire. Conclusion: The SDI is relevant and easy to understand. Initial psychometric evaluation was encouraging. Ongoing work to evaluate the clinical meaning and utility of the instrument and to examine the relationships between SDI scores and clinical outcomes will provide guidance about its usefulness as an assessment tool in routine oncology practice.Presented in part at the British Cancer Research Meeting (poster presentation) 2001 and at the World Congress of Psycho-Oncology (poster presentation) 2003.